When the Sabbath commences, we should place a guard upon ourselves, upon our acts and our words, lest we rob God by appropriating to our own use that time which is strictly the Lord’s. We should not do ourselves, nor suffer our children to do, any manner of our own work for a livelihood, or anything which could have been done on the six working days. Friday is the day of preparation. Time can then be devoted to making the necessary preparation for the Sabbath and to thinking and conversing about it. Nothing which will in the sight of Heaven be regarded as a violation of the holy Sabbath should be left unsaid or undone, to be said or done upon the Sabbath. God requires not only that we refrain from physical labor upon the Sabbath, but that the mind be disciplined to dwell upon sacred themes. The fourth commandment is virtually transgressed by conversing upon worldly things or by engaging in light and trifling conversation. Talking upon anything or everything which may come into the mind is speaking our own words. Every deviation from right brings us into bondage and condemnation.
~ Testimonies for the Church, Vol. 2, p. 702